This invention relates generally to a Tee nut and the method of manufacturing thereof, and more particularly to a Tee nut formed with improved pawls and barrel configuration and method of manufacture thereof to provide improved performance of the nut.
Background Art
The use of Tee nuts as anchors in wood or plastic or composite or other base material into which screws are threaded is well-known in the art. These are especially useful in the manufacturing of furniture. Conventionally Tee nuts include a flange which typically will have pawls extending therefrom to engage the base wood or other material and prevent rotation of the Tee nut and secure the Tee nut in the material. The Tee nut also has an elongate generally cylindrical barrel which is conventionally threaded internally with female threads. In some instances the threading extends only partially within the barrel from the flange at the proximal end portion to the beginning of the distal end portion with the distal end portion being smooth and often having a larger inside diameter than the proximal end portion.
While the pawls may have several different forms e.g. as shown in U.S. Pat. No. 5,503,596 these various pawl forms have limitations or drawbacks either in their effectiveness in holding the Tee nut in place or in the technique of manufacturing the pawls or hampering the feeding of the Tee nuts in automatic feeders.
FIG. 1 shows a side elevational view and FIG. 2 shows a top plan view of one embodiment of a prior art Tee nut and FIG. 3 shows schematically a problem known as shingling encountered when the prior art Tee nuts of FIGS. 1 and 2 are conveyed in a feed track. This shingling occurs when the flange portion of one Tee nut overrides the flange portion of an adjacent Tee nut during feeding thus causing jamming or improper feeding. Moreover, the pawls of the Tee nut shown in FIGS. 1 and 2 while particularly useful for inserting the Tee nut in soft wood, if these types of pawls are used in a plastic or dense wood product, the prongs tend not to penetrate the material but to fold over during insertion. This can cause the part to spin when the bolt is inserted into the part. Thus, the prior art Tee nut of FIGS. 1 and 2 has some significant problems in feeding and is limited in its use.
FIG. 4 is a side elevational view of a another embodiment of a prior art Tee nut and FIG. 5 is a plan view of the Tee nut of FIG. 4. FIG. 6 depicts somewhat schematically a problem encountered when the Tee nut of FIGS. 4 and 5 is utilized in an automatic feed track. As can be seen in FIG. 6, the small upwardly projecting pawl can tend to jam in the feed track thus preventing proper feed of the Tee nut. Moreover, the pawl configuration in the Tee nut of FIGS. 4 and 5 is especially useful in plastic and very dense wood. However, in plywoods or other soft woods this pawl, due to its shape and size, tends to rotate when the bolt is installed. Thus, the prior art Tee nut shown in FIGS. 4 and 5 has limitations in its use and significant drawbacks in its ability to be fed in an automatic feeding track.
Also, the technique of forming the barrel e.g. as shown in U.S. Pat. No. 5,503,596 has several drawbacks and limitations. These includes a shallow, and thus less desirable lead angle, and non-uniform barrel lengths.